Great questions, relays can get complicated, especially since relay policy isn't surfaced super well. To get some hints on what a particular relay may or may not accept, you can look at the NIP 11 relay document and watch for error messages contained in NOTICE or OK messages. This may help explain why your notes are being rejected.

It's odd that primal would reject notes from their own users. For most of the rejections, I doubt that WoT would be the reason, since wot filtering is a relatively new thing on the relay side and not supported by a lot of relay implementations. My best guess would be rate limiting, or over-zealous spam filtering after the last few weeks of ReplyGuy.